1. Field of the Invention
The present invention relates to a magnetic tape cassette. More particularly, it relates to an improvement of the structure of the front part of a video tape cassette.
2. Description of the Prior Art
Heretofore, two kinds of magnetic video tape cassettes have been known.
In the conventional tape cassettes, the VHS type video tape cassette has a structure shown in FIG. 1. That is, a lower casing (1) and an upper casing (2) are molded so as to form an assembled casing. A magnetic tape wound on a winding hub (not shown) is placed in the assembled casing and then the lower casing and the upper casing are screwed together. A mechanism for guiding the magnetic tape outside is provided at the front part of the lower casing and the upper casing respectively. A pin (3) for drawing the magnetic tape outside is provided at a side of the front part of the lower casing (1) and another pin (4) for taking the magnetic tape inside is provided at the other side of the front part of the lower casing (1) and a pair of guide ribs (5) are formed between the pins (4) and (5). Each guide rib has a projecting bead (6) at its lower edge so that the lateral movement of the magnetic tape (vertical direction in the drawing) can be prevented. The surface of the rib (5) is formed in a vertical plane to guide the magnetic tape. Similarly, a pair of guide ribs (7), (7), and outlet (8) of the magnetic tape and an inlet (9) of the magnetic tape are formed at the front part of the upper casing. The guide ribs (5) and (7) are formed in such a manner that the faced ends of both guide ribs just fit at the central plane formed in the assembled casing as shown in FIG. 2. The magnetic tape (T) is guided by a vertical surface formed by both guide ribs (5), (7).
In the conventional tape cassette, serious difficulty has been found in assembling the casings. That is, in the course of the assembling operation in which the magnetic tape wound on the winding hub is placed in the predetermined position of the lower casing (1) and a part of the magnetic tape is taken out from the area of the pins (3) and (4) to pass in front of the guide ribs (5), (5) and the upper casing (2) is laid over the lower casing (1) as shown in FIG. 2, the magnetic tape is often bitten, snagged or pinched between the faced ends of the guide rib (5) and the guide rib (7) since the magnetic tape (T) extends over the central plane (11).